From the standpoint of cybernetics, organisms are systems with a memory. Their behaviour at a particular instant is not affected only by the momentary combination of stimuli arriving at their inputs from the surroundings, but also by a combination of the stimuli that they encountered in the past. Organisms have, in principle, two types of memory: individual memory, i.e. memory storing information about stimuli that the organism encountered during its lifetime, and evolutionary memory, storing information about the stimuli that its near and distant ancestors encountered. The relevant components of the physical structure of the body of an organism are the carriers of the individual memory. The amount of stored fat can reflect the amount of foodstuffs consumed, while a missing leg or chewed-off leaves could provide information on an encounter with a natural enemy, a predator or an herbivore. In animals, the extraordinary capacity for individual memory is characterized by special organs – the nervous and immune systems. In modern organisms, nucleic acid, in most cases DNA, is the carrier of evolutionary memory. Information stored in individual memories can be useful from the standpoint of survival of the individual, but can also be detrimental (e.g. the above-mentioned missing leg, or experience gained in consuming an addictive drug). In contrast, evolutionary memory always bears information that is useful for the organism from the standpoint of the probability of its survival and reproduction or is at least not detrimental from this point of view. Information is accumulated in the DNA and changed through random mutations and thus, immediately after its formation, can be either useful or detrimental for its carrier; however, only information that objectively and in the long term augments, or at least does not reduce, the probability of survival and reproduction of its carrier, i.e. the organism in whose genome it is located, has a chance to become a permanent part of the gene pool of the particular species. This chapter will be concerned with the properties of evolutionary memory and also the specific mechanisms of creation and implementation of genetic information and its passing down from one generation to the next. The manner of functioning of evolutionary memory prior to the formation of contemporary living systems, functioning on the principle of coexistence of proteins and nucleic acids, will not be discussed here, but rather in Chapter X, which is concerned with the origin of life. A great many aspects of the effect of multi-cellularity and the differentiation between the germinal and somatic lines of cells on the manner of passing down genetic information will be further discussed in Chapter XII (Ontogenesis and Life-Cycle Evolution).